Automated method for cutting tissue retainers on a suture

ABSTRACT

An automated method for manufacturing self-retaining suture is disclosed. The suture is mounted to a support. A power-operated cutting arm moves a cutting device through the suture along a preselected path and at a preselected angle to create a tissue retainer having a desired shape and size. The suture is indexed relative to the cutting device. The operation of the cutting arm in conjunction with the geometry of the cutting device and linear advancement of the suture thread allows for creating a plurality of tissue-retainers having a desired geometry along the length of the suture thread.

CLAIM TO PRIORITY

This application is a continuation of U.S. application Ser. No. 11/691,845, filed on Mar. 27, 2007, now pending; which is a continuation of U.S. application Ser. No. 10/486,123, filed Jul. 2, 2004, now U.S. Pat. No. 7,225,512, issued Jun. 5, 2007; which claims priority under 35 USC §371 to PCT/US2002/027525, filed on Aug. 29, 2002, published on Mar. 6, 2003 under Publication No. WO03/017850A1, now expired; and is a continuation-in-part of U.S. application Ser. No. 09/943,733, filed Aug. 31, 2001, now U.S. Pat. No. 6,848,152, issued Feb. 1, 2005. All of the above claimed priority applications are incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method of barbing suture filament by varying the blade geometry and/or the movement of a blade when cutting a suture filament where the method can also be utilized to cut a plurality of axially spaced barbs on the exterior of sutures and an apparatus for performing this.

2. Description of the Prior Art

In the prior art, it is well known that surgical and traumatic wounds are typically closed with a filament introduced into the tissue by a needle attached to one end. Closure of the wound and holding tissues together supports healing and re-growth. What is typically used for this procedure is known as a suture.

A barbed suture is a one-way suture which allows passage of a needle-drawn suture in one direction through tissue, but not in the opposite direction. A barbed suture is generally an elongated body having a pointed leading end and a plurality of axially and circumferentially spaced barbs on the exterior surface of the elongated body.

In closing a wound with a barbed suture, the suture is passed through tissue at each of the opposed sides of a wound. Suture pairs are formed in which trailing ends of sutures are positioned generally in alignment at opposite sides of the wound. On insertion of each suture, the needle is pushed to extend out of the tissue at a point laterally remote from the wound, then the needle is pulled out to draw the suture to the desired position, and the suture is then severed from the needle. (Note that methods of using barbed sutures are disclosed in copending U.S. patent application Ser. No. 09/896,455, filed Jun. 29, 2001, entitled “Suture Method” and assigned to Quill Medical, Inc., the disclosure of which is incorporated herein by reference.) The advantage of using barbed sutures is that there is an ability to put tension in the tissue with the result of less slippage of the suture in the wound. The number of suture pairs is selected in accordance with the size of the wound and the strength required to hold the wound closed. Although tissue anchoring is easier done with a very pointed barb and a relatively skinny tip, better tissue holding results are obtained with a fuller tip barb.

In some circumstances of tissue repair, a random configuration of barbs on the exterior of the suture might be preferred. With as many barb angles as possible, superior wound holding would be achieved. However, in other circumstances where the wound or tissue repair needed is small, a small suture would be preferable. A small suture would require a reduced number of barbs on the exterior of the suture. Various methods of cutting the barbs have been proposed (see e.g. U.S. Pat. No. 5,931,855). However, such methods have not been commercially exploited for reasons which are unclear.

It is seen from the foregoing that there is a need for a method of cutting barbs on the exterior of sutures with a minimum of difficulty and in a reliable and relatively economic fashion so as to allow for the wide spread commercialization of such sutures. Such a method should also be able to vary the size of the barbs, their location and depth to allow for variation thereof and versatility of their application. The method should be able to cut a plurality of barbs with the positioning depending on the number of barbs needed. The need also exists for a device able to use the method described above which can provide a plurality of axially spaced barbs either in a random or similar configuration, with the configuration depending upon, among other things, the type of tissue being repaired.

SUMMARY OF THE INVENTION

It is therefore a principal object of the present invention to provide for a practical method of cutting barbs in a suture.

It is therefore a further object of the present invention to provide a method for cutting fuller tipped barbs of various sizes on the exterior of a suture.

It is therefore a still further object of the present invention to provide a method for cutting a plurality of axially spaced barbs on the exterior of a suture.

It is therefore a still further object of the present invention to provide a method for cutting a plurality of axially spaced barbs circumferentially about the exterior of a suture.

It is therefore a still further object of the present invention to provide a method for cutting a plurality of axially spaced barbs in similar or random configurations on the exterior of a suture.

It is therefore a yet further object of the invention to provide for an illustrative apparatus to perform this method.

To attain the objects described, there is provided a cutting method which produces suture barbs of varying sizes depending on the geometry of the blade being used and/or the movement of the blade when cutting into a suture. By altering the blade geometry and/or degree or trajectory of blade movement, the barbs can be made of varying sizes designed for various surgical applications. For example: for joining fat and relatively soft tissues, larger barbs are desired, whereas smaller barbs are more suited for collagen intensive tissues. Also, the use of a combination of large and small barbs on the same suture will ensure maximum anchoring properties wherein barb sizes are customized for each tissue layer.

The cutting method may be achieved with a cutting device disclosed herein. The device disclosed can produce six sets of barbs in staggered positions along the length of a suture, such that three sets of barbs are faced opposite to another three sets of barbs. Viewing the suture on a cross-sectional plane, the barb sets would be positioned either 120 or 180 degrees to each other, depending on the cutting method. Longitudinally, each barb cut would begin where the nearest one ends.

Compared with the method of cutting barbs in an untwisted state, using the twisted configuration can simplify production equipment; produce a stronger suture; reduce production cycle time by at least a factor of three; and be easily scalable to smaller diameters and produce barbs in a spiral fashion rather than at 120 or 180 degrees.

By way of variations, slight modifications, and/or combinations of the methods of cutting with and without twisting the suture, barbs can be obtained with random configurations. There are instances in tissue repair that the random configuration may be ideal to anchor tissues in as many barb angles as possible to provide superior wound holding properties. These and other objects and characteristics of the present invention will become apparent from the further disclosure to be made in the detailed description given below.

BRIEF DESCRIPTION OF THE DRAWINGS

Thus by the present invention its objects and advantages will be realized the description of which should be taken in conjunction with the drawings wherein

FIGS. 1A-F depict the cutting motion of a blade with one degree of freedom from movement and two degrees of freedom from blade geometry.

FIGS. 2A-C depict the cutting motion of a blade with two degrees of freedom from blade movement and one degree of freedom from blade geometry.

FIGS. 3A-C depict they cutting motion of a blade with three degrees of freedom from blade movement and a solid plane geometry.

FIGS. 4A-C depict a zigzag (oscillating back and forth and downward) cutting motion of a blade with three degrees of freedom from blade movement and solid plane blade geometry.

FIGS. 5A-C depict the cutting motion of an articulating blade with three degrees of freedom from blade movement.

FIG. 6 is a top view of the assembled cutting device.

FIG. 7 is a perspective view of the cutting bed.

FIG. 8 depicts an end, a side, and a cross-sectional view of the retention knob of the cutting device.

FIG. 9 depicts a top and side view of the blade assembly of the cutting device and a top view of an example blade for the blade assembly.

FIG. 10 depicts a top and side view of the template block of the blade assembly.

FIG. 11 depicts a top and side view of the cutting template used with the cutting device.

FIGS. 12A-B depict a top and side view of the tamp used with the cutting device.

FIG. 13 depicts the securing of the suture to the retention knob and placement on the spacing bar.

FIG. 14 depicts the placement of the various fixtures used with the cutting bed vise.

FIG. 15 depicts the blade assembly placement and downward movement in relation to the cutting template with the rest of the cutting device removed from the figure for clarity purposes.

FIG. 16 depicts the blade assembly placement and upward movement in relation to the cutting template.

FIGS. 17A-F are front views depicting the setting of barbs in the cutting bed vise before and after cutting using the 120 degree rotation method of cutting.

FIGS. 18A-B are front views depicting the setting of the suture in the cutting bed vise before cut using the twisting method of cutting.

FIGS. 19A-D depict the various conditions of a suture before and after the twisting method of cutting.

FIG. 20 is a side, top and detail view of a barbed suture using the 120 degree rotation method of cutting.

FIGS. 21A-C depict perspective views of a linear indexing mechanism with a rotary reciprocating blade assembly.

FIG. 22 is a perspective view of a rotational indexing mechanism with a rotary reciprocating blade assembly.

DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS

We refer now to the drawings in detail wherein like numerals refer to like elements throughout the several views.

The purpose of the present invention is to provide for an effective way of producing a barbed suture. In this regard, several different types of methods are disclosed which are directed to the cutting action of a blade on the suture to create the barbs. As will be described, the cutting action envisioned takes into account the movement of the blade and the blade geometry.

Essentially, the cutting of the suture with a blade takes into account three dimensions x-y-z of the suture 6. Each dimension is important and may be addressed by the cutting motion of the blade and/or the blade geometry. Depending on the blade geometry, the blade movement can have an effect in the other dimensions.

In this regard, FIG. 1A illustrates a consistent cutting motion of a blade 8 with one degree of freedom of movement and two degrees of freedom from blade geometry across a suture 6. One degree of freedom from movement is movement in one direction in a three-dimensional “x-y-z” layout. For FIG. 1A, direction 2 follows the lateral “x” axis in the cut of suture 6, with the movement of blade 8 in direction 2 before accomplishing a cut. An edge 10 of blade 8 has an angle, depicted as 12, in its blade geometry between the tips of sides 14, 16 of blade 8, as well as an angle (not shown) in its blade geometry between the top and bottom planes of blade 8. Such a geometry will cause an effect in the y and z dimensions (i.e. in the length and depth of the barb) just by the movement of blade 8 in the x direction.

As shown in FIG. 1B, these angles allow a cut into suture 6 in the y and z directions during movement in direction 2. This cutting-into movement is depicted as resultant direction 18. FIG. 1C depicts the completed cut of suture 6 with a continued movement in direction 2 away from the suture 6.

Similar to FIG. 1A, FIG. 1D illustrates a cutting motion of a blade 8 with one degree of freedom of movement and two degrees of freedom from blade geometry across a suture 6. In FIG. 1D, blade 8 is a hollow ground blade, in which edge 10 has an angle in its blade geometry between the tips of its sides 14, 16, as well as a concave or curved-in face in its blade geometry between the top and bottom planes of blade 8. Such a geometry will cause an effect in the y and z dimensions (i.e. in the length and depth of the barb) just by the movement of blade 8 in the x direction.

As shown in FIGS. 1E and 1F, this blade geometry allow a cut into suture 6 in the y and z directions during movement of blade 8 in direction 2. Comparison of FIG. 1E with FIG. 1F illustrates how movement of blade 8 in direction 2 increases the length and depth of the barb.

Turning now to FIGS. 2A-C, a consistent cutting motion of a blade with two degrees of freedom of movement and one degree of freedom from blade geometry is illustrated. Two degrees of freedom of movement is movement in two directions x and y. For FIG. 2A, direction 2 follows the lateral “x” axis and direction 22 follows the forward “y” axis in the cut of suture 6. In this regard the movement of blade 8 in two directions 2 and 22 simultaneously may be used to accomplish a cut. Edge 10 of blade 8 is at an angle of 90° or less, depicted as 24, of one degree in its blade geometry between the tips of sides 14, 16 of blade 8.

As shown in FIG. 2B, forward movement in direction 22 and along a lateral direction 2 allows a longer cut into suture 6 than produced in FIG. 1, since in FIG. 1 the blade geometry and blade movement in the x-axis determines the length of the barb, whereas in FIG. 2 the blade geometry and blade movement along both the “y” and “x” axes determines the length of the barb. This longer cutting action is in the “y” direction. FIG. 2C shows the completed cut of the suture 6 with a continued movement in direction 2 away from the suture.

FIG. 3A illustrates a further consistent cutting motion of a blade with three degrees of freedom of blade movement and edge 10 of 90° or less. Three degrees of freedom from movement is movement in the three directions of a three-dimensional “x-y-z” layout. For FIG. 3A, direction 2 follows the lateral “x” axis, direction 22 follows the forward “y” axis and direction 32 follows the downward “z” axis. The movement of blade 8 in all three directions 2, 22 and 32 may be used to accomplish the cutting of a barb on the suture 6.

The combination of movement in lateral direction 2, forward direction 22 and downward direction 32 would allow one to vary the length and depth of the cut to create a barb. It may be a deeper barb by cutting further in direction 32 and/or a longer barb by cutting further in direction 22. By moving blade 8 in lateral direction 2, forward direction 22 and downward direction 32 simultaneously forms a trajectory, which may be altered to create barbs with different qualities such as aspect ratios. FIG. 3C shows the completed cut of suture 6 with a continued movement in directions 2, 22, and 32 away from the suture 6.

A yet further method of cutting a barb is shown in FIGS. 4A-C where a back and forth or zigzag (oscillating on the “x” axis combined with the movement in z and/or y axis) motion of the blade with three degrees of freedom of blade movement and a solid plane geometry cuts the barb with a saw-like cutting motion. Three degrees of freedom of movement is movement in three directions in the three-dimensional “x-y-z” layout. In FIG. 4A, direction 2 follows the lateral “x” axis, direction 22 follows the forward “y” axis, direction 32 follows the downward “z” axis, and direction 42 follows the lateral “x” axis except in a direction opposite to direction 2. FIG. 4A shows the movement which may be used to accomplish a cut of blade 8 in directions 22 and 32 with alternation in movement between directions 2 and 42. Edge 10 of blade 8 would be straight between the tips of sides 14, 16 of blade 8.

The combination of alternating movement in lateral directions 2 and 42, steady movement in forward direction 22 and steady movement in downward direction 32 allows the depth of the cut to be varied. The resultant zigzag cutting motion is shown as alternating direction 44 in FIG. 4B. FIG. 4C shows the completed cut of suture 6.

A still further method of cutting a barb is shown in FIGS. 5A-5C where articulation of blade 8 about an axis 9, in combination with any of the cutting motions described in FIG. 14 above, may be used to vary the depth of the barb. In FIG. 5A, direction 2 follows the lateral “x” axis (into the plane of the drawing), direction 22 follows the forward “y” axis and direction 32 follows the downward “z” axis. FIG. 5B shows the blade movement which may be used to accomplishing a cut of blade 8 in directions 2 and 22, similar to that depicted in FIG. 2B. Forward movement in direction 22 and along a lateral direction 2 produces a barb based on two degrees of freedom of blade movement. In FIG. 5C, blade 8 is also allowed to articulate about axis 9, providing an additional degree of freedom, which may be used to impart additional barb depth in direction 32 in the z-axis. This articulating motion of blade 8 may be employed in combination with any of the blade geometries and/or blade movements previously described. Articulation of blade 9 may also be used to lift a cut barb up and away from the surface of suture 6, thereby leading to a fuller or more pronounced barb.

The blade motion shown in FIGS. 1-5 can cut a suture filament made of polyglycolide, polydioxinone, polypropylene, other resorbables, other nonresorbables, Gore-Tex ®, bi-component material or sutures made of other material suitable for the purpose.

While in the aforesaid examples, only a single blade is shown, it is envisioned that a plurality of blades may be utilized. They may be in tandem or on a rotary mechanism or on any other type of mechanical device which effects the implementation of the movement so described. Also, while the suture is shown in an untwisted state, it may be cut in a twisted state as hereinafter described.

By way of examples of mechanical devices for implementing the foregoing, reference is made to FIGS. 6-19 and 21-22. It should be understood, however, that these devices should not be considered exclusive and other types of devices for such implementation are contemplated.

Turning now more particularly to FIG. 6, there is shown a cutting device 50 that allows an operator to cut multiple barbs on the exterior of suture 6 using the methods previously described. The cutting device 50 includes retention knobs 52, 54 for retaining the suture 6 on a vise 63 during cutting. Retention knobs 52, 54 include knob holders 61, 62. Cutting bed vise screws 58, 60 are used to open and to close cutting bed vise 63, where suture 6 is placed during cutting.

A cutting template 64 directs the cutting motion of a blade assembly 66 containing a plurality of blades across suture 6. Two additional cutting templates are provided for operation of the cutting device but are offset to provide a different axial position of the blades with respect to suture 6. The cutting templates have the same configuration as cutting template 64 and are installed in a similar manner throughout the several views. Also, while the templates shown are particularly suited for practicing one way of cutting the barbs, such templates can be readily modified to allow the performance of other ways, including those previously described as will be appreciated by a skilled artisan.

Cutting bed vise 63 assists in the alignment of the cutting templates. On the top of block 68 of cutting bed vise 63 are two protrusions. These protrusions are alignment pins 70, 72 which are used for setting the cutting templates and a tamp 101.

As will be apparent to one skilled in the art, the configuration of cutting bed vise 63 may vary. If the suture is rotated (e.g. 120 degrees or 180 degrees) to effect cutting barbs about its circumference, the cutting bed vise may be configured as shown in FIG. 6. If the suture is twisted prior to cutting, as will be discussed, the cutting bed vise 63 preferably has a configuration with trapezoidal sides such as those shown in FIG. 7. Because suture material is somewhat compliant, this design provides superior clamping to a vise with parallel sides. Note that the vise shown in FIG. 7 can also be used with a rotated suture, since there is a space to accommodate a cut barb. In this regard, in FIG. 7, blocks 68, 74 taper outward from the tops on their interior sides to a surface 76, with the blocks depicting a trapezoidal shape when viewed from an end profile. Protruding from the taper of block 68 is a trapezoidal or anvil suture clamp 78 which is used to secure suture 6 during the closing of cutting bed vise 63. Suture clamp 78 is a wedge shape which sets on surface 76 and ends slightly below top 80.

In addition to securing suture 6, retention knobs 52, 54 are rotated between the various cutting methods and are numerically indexed for precise movement. As depicted in FIG. 8, retention knob 52 is a solid elongated body. Retention knob 52 comprises a cylinder 82 having a gripping area 84 integral with a triangular protrusion 86. Triangular protrusion 86 can rest on cutting bed 56 or a spacing bar 100, shown in FIG. 13. An anchor screw 90 secures suture 6 to the retention knob. The triangular protrusion includes numerical marks for guiding the operator in positioning the retention knob during various stages of the cutting method; however, the triangular protrusion may be indexed in other variations. One side of the triangular protrusion has the number “1” imprinted, another side has the number “2” imprinted and a third side has the number “3” imprinted. Retention knob 54 has the same characteristics as retention knob 52.

For cutting a plurality of barbed sutures at one time, a multi-blade assembly is used. As depicted in FIG. 9, blade assembly 66 consists of a plurality of blades 8 secured in retaining block 92. In FIG. 8, thirteen blades are depicted, although obviously the number of blades used may vary. Edge 10 of each of the blades used in the blade assembly 66 would extend through a template block 94, shown in FIG. 10 by the amount of the desired barb depth.

Retaining block 92 of FIG. 9 consists of two rectangular blocks which retain blade assembly 66 by a vise action. Blade assembly 66 conformingly fits to a cutaway section of the retaining block and blades 8 are inserted at a desired angle, which in this case is 148 degrees. The blades are secured in the retaining block 92 with the template block 94 attached thereto. Template block 94 acts as a guide for the blade assembly within the confines of the cutting templates.

As shown in FIG. 11, the cutting template 64 provides a cutting path 97 for blade assembly 66. Cutting path 97 is shown as a parallelogram perimeter. Note, however, for example, the cutting path 97 may be shaped with a rectangular perimeter to suit the movements described in the cutting method of FIG. 1, or other shapes to permit additional degrees of blade movement as described in FIGS. 2-5. Additional cutting templates are provided and are similarly made with the purpose of offsetting the blade cut in an axial direction. The cutting template 64 is identified so as to indicate to the user which one is to be used at which stage of cutting. On opposite sides of the cutting template 64 is a channel 99 sized to accommodate the other sections of suture 6 not being cut by blade assembly 66.

As shown in FIG. 12A, a tamp 101 is provided to insure that suture 6 is uniformly seated on the anvil 78. Apertures 102, 104 on tamp 101 are provided to engage the alignment pins 70, 72. A channel 105 is provided to hold suture 6 in place during the calibration. The depth of the channel 105 equals the thickness of the suture 6 above vise top 80.

To operate cutting device 50, first one secures the suture 6 to anchor screws 90 on one of retention knobs 52, 54 as shown in FIG. 13. Retention knob 52 is placed on the ledge of spacing bar 100 with the suture 6 drawn there-across with the second retention knob 54 positioned on the opposing ledge. The suture should not be overly taut once it is secured to the second retention knob by anchor screw 90. After sizing, suture 6 is placed on cutting bed 56 and held in place by cutting bed vise 63. The retention knobs 52 and 54 are indexed in a first position. As will be apparent in a second and third cutting for a barbed suture having barbs spaced 120 degrees apart, retention knobs 52 and 54 are rotated to second and third positions respectively.

As shown in FIG. 14, the tamp 101 is placed on the cutting bed 56 positioning the suture 6 in vice 63 which is tightened, and the tamp is then removed. Cutting template 64 is then placed onto cutting bed 56.

In the cutting method of suture 6, blade assembly 66 is placed onto cutting bed 56. The blade assembly is pressed down while slid from the top of the cutting template to the bottom along path 97 as shown in FIG. 15. The blade depth is set to produce the desired depth of the barb. After blade assembly 66 stops at the bottom of cutting template 64, the blade assembly is removed. To create barbs in a direction opposite those first cut, blade assembly 66 may then be turned 180 degrees and placed onto cutting bed 56 as shown in FIG. 16. The left and top of the blade assembly are in contact with the right and bottom of the cutting template along path 97. The blade assembly is pressed down while the blade assembly is slid from the bottom to the top. After the blade assembly 66 stops at the top of cutting template 64, the blade assembly and the template are removed.

As the process proceeds, suture 6 may be rotated, e.g. 120 degrees, 180 degrees, etc., and the cutting process repeated as shown in FIGS. 15-16. The suture should be set securely in the opening of cutting bed vise 63 and previously cut barbs should not project above top surface 80, and the process is repeated. For three sets of barbs about the circumference, the suture is rotated three times, for two sets, two times, etc.

FIG. 17A-F shows the setting of the barbs in vise 63 before and after cutting for a suture having barbs spaced 120 degrees apart. FIG. 17A shows the vise open, suture 6 uncut, with vise notches 120, 122 unused. FIG. 17B shows the vise closed with blade assembly 66 about to cut suture 6. FIG. 17C shows the vise opened after the first set of barbs are cut and placed in notch 122. FIG. 17D shows the vise closed before blade assembly 66 engages suture 6 to cut the second set of barbs. FIG. 17E shows the vise open with two sets of barbs shown and placed in notches 120, 122. FIG. 17F shows the vise closed before blade assembly 66 engages suture element 6 for the cut. After cutting, the suture 6 is removed and examined. As will be apparent to a skilled artisan, additional or fewer notches may be provided for protecting barbs during subsequent cutting steps.

In the twisting method of cutting barbs, suture 6 is set up as previously described and twisted along its axis. The number of twists required is dependant upon the number of barbs, the material of the suture and the diameter of the suture. For example, it has been found that size 0, PDS-2 material requiring 2-½″ of barbs would require twisting it thirty-nine times for an acceptable result. Of course, too much twisting may cause the suture material to overrun itself, leading to undesirable results including damaged suture material.

The securing of a twisted suture 6 on cutting bed 56 is, however, slightly different. In this regard, FIGS. 18A and B show the setting of suture 6 in clamp 76 before and during cut. FIG. 18A shows suture 6 being placed in the vise prior to clamping, with FIG. 18B showing the suture post clamping. The lightly clamped suture 6 forms an elliptical shape and is ready to be cut. The cutting method of suture 6 would be the same as that afore-discussed without, however, the need for the suture to be rotated.

FIGS. 19A-D show the various conditions of suture 6 using the twisting method of cutting. In FIG. 19A the suture 6 is shown unmodified, with an imaginary line 150 shown to depict its longitudinal axis. FIG. 19B shows the suture 6 as it is twisted in direction 152 in preparation for cutting. FIG. 19C shows barbs cut in the twisted condition, with barbs cut along one side thereof. After the suture 6 has been cut and allowed to return to its untwisted condition, the barbs are such as those shown in FIG. 19D where the barbs spiral around the circumference of the suture.

The difference in the placement of the barbs in the twisted versus the untwisted method can best be seen by comparing FIG. 19D with FIG. 20. In FIG. 20, the suture 6 cut in the untwisted state is shown with spaced barbs at 120° about the circumference of the suture 6. In FIG. 19D, the suture 6 was cut in the twisted state, and, upon de-twisting, the pattern of the barbs takes on a spiral configuration along the length of the suture 6.

Note that by omitting cutting motions when suture 6 is cut in either a twisted or untwisted state, the barbs can be formed in a random configuration on the exterior of the suture. Also, the suture may be cut in both a twisted and untwisted state to produce other types of random configurations of barbs.

Alternate embodiments for cutting barbs according to the present invention are shown in FIGS. 21-22. FIGS. 21A-C show a linear indexing mechanism for advancing suture 6 along cutting bed vise 63 in direction 22, while reciprocating blade assembly 250 cuts barbs along the axis of suture 6. Suture 6 may be advanced along cutting bed vise 63 in a twisted state to form spiral cut barbs as shown in FIGS. 21A and B, in an untwisted state, or rotated about its axis in increments (e.g. 120 degrees, 180 degrees, etc.) as it advances as shown in FIG. 21C.

Reciprocating blade assembly 250 includes blade 8 connected via arm 225 to a linear reciprocating solenoid 220, which reciprocates in direction 2 and 42 corresponding to the x-axis, and to rotary solenoid 230, which can turn about its axis as shown in FIGS. 21A and B. Cutting bed vise 63 is synchronized with reciprocating blade assembly 250 and the indexing mechanism such that the vise closes to hold suture 6 in place during cutting and opens to allow suture 6 to be advanced by the indexer to the next cutting position.

Linear solenoid 220 and rotary solenoid 230 may be adjusted to control the linear stroke and blade angle of arm 225 of reciprocating blade assembly 250 to allow for varying the depth of the barbs cut in the y and z axes. In addition, rotation of rotary solenoid 230 allows barbs to be cut in the opposite direction along the axis of suture 6 as shown in FIG. 21B. The blade angle and stroke may also be adjusted to sever suture 6 at any desired length.

FIG. 22 shows a rotational indexing mechanism for advancing suture 6. In FIG. 22, suture 6 is shown advancing around a rotating drum 210, while reciprocating blade assembly 250 cuts barbs along the axis of suture 6. Suture 6 is fed onto drum 210 and into cutting channel 215 via suture supply spool 300. Barbed suture is wound off drum 210 onto take-up spool 310. Spools 300 and 310 may supply and take up suture 6 in an untwisted state, or alternatively, either or both spools may be rotated in such a way as to twist and untwist suture 6 to allow spiral cut barbs as described above.

While the invention has been described in connection with what is considered to be the most practical and preferred embodiment, it should be understood that this invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

1. A method for cutting barbs on a suture thread having a longitudinal axis, the method comprising: (a) setting the suture thread on a support; (b) actuating an electrically-operated reciprocating blade assembly to create a first barb at a first location on the suture thread; (c) indexing the suture thread along the longitudinal axis; and (d) actuating the electrically-operated reciprocating blade assembly to create a second barb at a second location on the suture thread longitudinally-displaced from the first location.
 2. The method of claim 1, further comprising repeating steps (c) and (d) a plurality of times to create a plurality of barbs at a plurality of locations.
 3. The method of claim 1, wherein step (c) comprises: (c1) indexing the suture thread along the longitudinal axis; and (c2) rotating the suture thread around the longitudinal axis.
 4. The method of claim 1, wherein step (c) comprises: (c1) indexing the suture thread along the longitudinal axis; and (c2) rotating the suture thread by 120 degrees around the longitudinal axis.
 5. The method of claim 1, wherein step (b) comprises: actuating an electrically-operated reciprocating blade assembly by actuating at least one transducer to move a blade through the suture thread to create a first barb at a first location on the suture thread.
 6. The method of claim 1, wherein step (b) comprises: actuating an electrically-operated reciprocating blade assembly by actuating at least one transducer to change a blade angle of the blade relative to the suture to create a first barb at a first location on the suture thread.
 7. The method of claim 1, wherein the support has an open configuration for moving the suture thread and a closed configuration for stabilizing the suture thread and wherein: step (b) comprises placing the support in the closed configuration and then operating a reciprocating blade assembly to create a first barb at a first location on the suture thread; and step (c) comprises placing the support in the open configuration and then indexing the suture thread along the longitudinal axis.
 8. The method of claim 1, wherein the support has a channel and step (a) comprises setting the suture thread on a support with a portion of said suture thread in the channel of the support.
 9. A method for cutting a suture thread having a longitudinal axis, the method comprising: (a) setting the suture thread on a support; (b) operating a power-operated blade assembly to make a first angled cut having a preselected configuration at a first location on the suture thread; (c) indexing the suture thread along the longitudinal axis; and (d) operating the power-operated blade assembly to make a second angled cut having said preselected configuration at a second location on the suture thread longitudinally-displaced from the first location.
 10. The method of claim 9, further comprising repeating steps (c) and (d) a plurality of times to make a plurality of angled cuts said preselected configuration at a plurality of locations.
 11. The method of claim 9, wherein step (c) comprises: (c1) indexing the suture thread along the longitudinal axis; and (c2) rotating the suture thread around the longitudinal axis.
 12. The method of claim 9, wherein step (c) comprises: (c1) indexing the suture thread along the longitudinal axis; and (c2) rotating the suture thread by 120 degrees around the longitudinal axis.
 13. The method of claim 9, wherein step (b) comprises: operating the power-operated blade assembly by actuating at least one transducer to make a first angled cut having a preselected configuration at a first location on the suture thread.
 14. The method of claim 9, wherein step (b) comprises: operating the power-operated blade assembly by actuating at least one transducer to change a blade angle of the blade relative to the suture and make a first angled cut having a preselected configuration at a first location on the suture thread.
 15. The method of claim 9, wherein step (c) comprises indexing the suture thread along the longitudinal axis utilizing a first spool to feed suture and a second spool to take-up suture thread.
 16. The method of claim 9, wherein the support has an open configuration for moving the suture thread and a closed configuration for stabilizing the suture thread and wherein: step (b) comprises placing the support in the closed configuration and then operating the power-operated blade assembly to make a first angled cut having a preselected configuration at a first location on the suture thread; and step (c) comprises placing the support in the open configuration and then indexing the suture thread along the longitudinal axis.
 17. The method of claim 9, wherein the support has a channel and step (a) comprises setting the suture thread on a support with a portion of said suture thread in the channel of the support.
 18. A method for creating tissue-retainers on a suture thread having a longitudinal axis, the method comprising: (a) setting the suture thread on a support; (b) operating a power-operated cutting assembly to cut the suture thread to make a first tissue-retainer having a preselected configuration at a first location on the suture thread; (c) indexing the suture thread along the longitudinal axis; and (d) operating the power-operated cutting assembly to cut the suture thread to make a second tissue-retainer having said preselected configuration at a second location on the suture thread longitudinally-displaced from the first location.
 19. The method of claim 18, further comprising repeating steps (c) and (d) a plurality of times to make a plurality of tissue-retainers having said preselected configuration at a plurality of locations.
 20. The method of claim 18, wherein the support has an open configuration for moving the suture thread and a closed configuration for stabilizing the suture thread and wherein: step (b) comprises placing the support in the closed configuration and then operating a power-operated cutting assembly to cut the suture thread to make a first tissue-retainer having a preselected configuration at a first location on the suture thread; and step (c) comprises placing the support in the open configuration and then indexing the suture thread along the longitudinal axis. 